The detection and characterization of specific nucleic acid sequences and sequence changes have been utilized to detect the presence of viral or bacterial nucleic acid sequences indicative of an infection, the presence of variants or alleles of mammalian genes associated with disease and cancers, and the identification of the source of nucleic acids found in forensic samples, as well as in paternity determinations.
For example, the RNA or DNA for many microorganisms and viruses have been isolated and sequenced. Nucleic acid probes have been examined for a large number of infections. Detectable nucleic acid sequences that hybridize to complementary RNA or DNA sequences in a test sample have been previously utilized. Detection of the probe indicates the presence of a particular nucleic acid sequence in the test sample for which the probe is specific. In addition to aiding scientific research, DNA or RNA probes can be used to detect the presence of viruses and microorganisms such as bacteria, yeast and protozoa as well as genetic mutations linked to specific disorders in patient samples.
Nucleic acid hybridization probes have the advantages of high sensitivity and specificity over other detection methods and do not require a viable organism. Hybridization probes can be labeled, for example with a radioactive substance that can be easily detected, or with biochemical markers such as, for example, biotin, that allows for their capture and detection. Nucleic acid molecules may also by captured by a first antibody that is specific to DNA hybrids, wherein the hybrids may comprise DNA-RNA hybrids, DNA-DNA hybrids or RNA-RNA hybrids. The hybrids may subsequently be detected by a second, labeled, antibody that may be, for example, labeled with a biochemical marker such as alkaline phosphatase or any other marker capable of detection.
As nucleic acid sequence data for genes from humans and pathogenic organisms accumulates, the demand for fast, cost-effective, and easy-to-use tests increases. There is a need to provide novel and effective methods, compositions, and kits for determining target nucleic acids in a rapid, cost-effective, and reliable manner in geographical areas where access to medical care is not readily available. There is also a need to provide these assays in a rapid-screen format that can be used in developing countries. The methods and assays of the present invention meet these needs and may be used in manual, partially automated, automated, and non-automated systems.
Clinical analysis in developing countries and geographical areas where access to medical care is not readily available presents unique challenges. The invention described herein achieves an acceptable resolution that balances the importance of these challenges in such countries and areas. For instance, speed in obtaining results is particularly important in locations where women travel great distances to provide specimens for analysis. In such locations, it is advantageous that results are obtained within several hours or the same day while the patient is still present to avoid loss to follow-up associated with traveling from home to the test site.
Other factors facing developing countries are the cost of running the assay and the instrumentation needed to run the assay. Repeat pipettors and single pipettes are just two types of devices that are routinely used in developed countries but are potentially cost prohibitive in developing countries. Accordingly, there is a need for medical devices and products which employ cheaper and more readily accessible alternatives in developing countries.